1. Field of the Invention
The present invention relates to a technique for generating information about jobs such as print jobs.
2. Description of the Related Art
Devices connected to a network to perform printing in response to a request from a computer or terminal via the network, such as printers and multifunction machines, have become available. Such network devices store a print log including information as to which users sent which print job requests. The stored print log is transmitted to the computer via the network, displayed on panels of the network devices, or is printed. The print log allows the administrators of the network devices to understand the usage status of the network devices. The print log generally includes information indicating a user name, a job name, the number of printed pages, a printing result, and the printing time.
Some of the network devices have no real time clock (RTC). Such devices obtain time information indicating the current time from a server on a network, and use the time information to perform processing later. One known method to obtain the time from a server is to use the simple network time protocol (SNTP) specified by RFC (Request for Comments) 2030.
SNTP provides three modes for a client to obtain time from a server. The first mode is a unicast mode. In the unicast mode, a client transmits a request to a specified server, and the server returns a response including time information to the client. The second mode is a multicast mode. In the multicast mode, a server periodically transmits time information to a local broadcast address or a multicast address, and a client receives the time information. The third mode is an anycast mode. In the anycast mode, a client transmits a request to a local broadcast address or a multicast address, and a server receives the request and returns a response including time information via unicast. In the anycast mode, when there are multiple servers, the client receives multiple responses. In this case, the client uses the first received response.
FIG. 1 shows the SNTP message format. The type of a request and response used in the three modes is identified by the value set in a “Mode”, field in the message format. The SNTP client function described above allows the network devices to obtain the current time even without the RTC function, and allows information indicating the printing time to be included in a print log.
Also, Japanese Patent Laid-Open No. 11-143665 discloses a printing control system for obtaining time information from a server using the network time protocol (NTP).
However, devices designed to obtain time information from a server on a network at the time of turning on power and to generate a print log using the time information sometimes experience problems when the devices fail to obtain the time information. If a device fails to obtain time information from a server for some reason, the device cannot specify the current time when printing is performed. Therefore, the device cannot generate a print log including printing-time information, and the device administrator does not know the printing time even when the administrator views the print log later.
It is therefore desirable to specify the job processing time even if a device fails to obtain time information. Or, it is desirable to prevent the job processing time from being set to unknown even if a device fails to obtain time information.